Growing evidence indicates that heavy metals leached into drinking water are an extremely serious and widespread environmental health hazard. The high toxicity of lead has long been known, but recent statistical medical studies have shown that even the smallest concentrations of lead in the body can cause serious health problems. Low-level lead exposure has been implicated in effecting fetal development (causing neurological, mental, and physical disabilities), in retarding the cognitive development of children, and in contributing to hypertension, heart attacks, and strokes in middle-aged men. In its report, "Reducing Lead in Drinking Water: A Benefit Analysis" (EPA-230-09-86-019; December, 1986), the Environmental Protection Agency (EPA) conservatively estimated that a billion dollars in annual monetized benefits would result from reducing exposure to lead in drinking water from 50 mg/l to 20 mg/l. Many people believe that zero lead is the ideal level.
High levels of tap water lead are found nationwide. It is especially a problem in areas with water of low to medium pH, with soft water, or with public water systems that contain sections of lead piping. In new homes, and those with new pipework solder, it is not uncommon to find first-draw water which contains lead in concentrations many times the EPA's current maximum contaminant level (MCL). Also, the leaching of copper ions from piping is a problem in some areas.
Many filters have been made to treat waters used in the home. Some have been designed to attach to the end of a water faucet or to place in the line just upstream of the tap. Some have replaceable and even regenerable elements; others are disposable. Many filters are used to remove hardness (calcium carbonates) from water. Other filters are used to remove unpleasant tastes or objectional colors in water. The filter of the invention is designed to remove toxic heavy metals, and, in particular, lead and copper from drinking waters. Moreover, the filter will, unlike conventional resin filters, selectively remove lead and copper ions and allow all other cations to pass through. This special ability gives the new filter long life before saturation occurs and therefore means that the filter can be relatively small and can be used effectively for a long time before requiring replacement.